Introduction of a new notched specimen geometry to determine fracture properties by small punch testing

The small punch (SP) testing technique can be used to assess fracture properties from a very small volume of material. However, the correlation of fracture parameters obtained from SP testing with those produced using standard methods is non-trivial, not only due to the size effect, but also due to the absence of a notch in most existing types of SP specimens. In the present study, a novel SP specimen design is proposed, with a sharp circular notch, leading to the development of a near plane strain condition during the SP test. The new geometry is examined through SP testing of P91 steel, as well as finite element analysis. Optical and scanning electron microscopy is used to study the crack propagation from the notch tip in both ductile and brittle fracture modes.